cell signaling

Question 1

What do cells need to do to respond to changes in the environment?

Answer 1

They must be able to receive and process signals from the outside

Question 2

How does the cell’s ability to respond affect itself?

Answer 2

its ability to tissue repair, protein activity, and apoptosis

Question 3

what is important about sharing pathways?

Answer 3

they are evolutionary lines of descent

Question 4

what kinds of distances chould cells communicate over

Answer 4

long and short

Question 5

what can happen from the same signal

Answer 5

They may have different results

Question 6

What is a chemical signal?

Answer 6

Signals made inside the body itself in a multicellular animal

(neurotransmitters)

Question 7

what are mechanical signals

Answer 7

touch

(touch receptors on skin)

Question 8

what are examples of external chemical signals?

Answer 8

immune response to pathogen

Question 9

What if the stimulus is a ligand?

Answer 9

it can work as an allosteric regulator

(reversible)

Question 10

What are some cell-to-cell communication mechanisms?

Answer 10

plasmodesmata and immune cells

Question 11

what is plasmodesmata?

Answer 11

small pores in plant cells and cell membranes that allow for the cytoplasm to move between cells and exchange info

Question 12

what are some cell communication ways over short distances

Answer 12

quorum sensing and neurotransmitters

Question 13

what is an immune cell?

Answer 13

antigen-presenting cell and helper T- Cell

Question 14

what is quorum sensing?

Answer 14

allows bacteria cells to know when numbers are high, allowing them to do a collective response

• signals turn on and off operons.. conserve energy accessing nutrients and defending against competitors

Question 15

what are neurotransmitters

Answer 15

chemical signals used to communicate between neurons: dopamine and serotonin.

Question 16

what are some cell communications over long distances

Answer 16

hormones like testostrone and insluin

Question 17

what are hormones

Answer 17

chemical signals that are released

Question 18

what is the signal transduction pathway?

Answer 18

if the cell has a particular receptor capable of detecting a stimulus, it will signal a sequence of molecular events

Question 19

how can the same signal impact different cells in different ways

Answer 19

ex:

-epinephrine - speed up heart, slow down digestion, initiates glycogen breakdown in liver

Question 20

what are the three stages of cell signalling

Answer 20

1) reception
2) transduction
3) response

Question 21

what is reception

Answer 21

when ligands (signal molecules) bind to receptors on cell, which changes the shape of the receptor

Question 22

where can the receptor be?

Answer 22

it can be..

-extracelluar like G-protein complex

-intracelluar like a small hydrophobic molecule like steroids

Question 23

what happens when there is a change in the receptor

Answer 23

it starts transduction of signals (cell’s response)

Question 24

what do cells often have

Answer 24

• hundreds of receptors
  -varying specific receptors
• combinations of signals to initiate responses

Question 25

what cells can respond to signals?

Answer 25

only cells with necessary receptors can respond

Question 26

what is an example of a short-term response?

Answer 26

activate/deactivate an enzyme

Question 27

what is an example of a long-term response

Answer 27

alter gene expression

Question 28

what are cell surface receptors

Answer 28

They hit the surface with a cell surface receptor protein and don't reach the nucleus. They have the hydrophilic signal molecule.

Question 29

what is an intracellular receptor

Answer 29

it uses a carrier protein to carry a signal molecule that is small and hydrophobic and reaches the nucleus

Question 30

what is transduction

Answer 30

(convert)

Question 31

what is a transduction cascade?

Answer 31

an intracellular chemical response to external signal

Question 32

how does the transduction cascade work?

Answer 32

1) external signal is converted to an internal signal cell which can respond to it (the internal signal cell is usually a TF) 2) Internal signals are amplified (few ligand receptors lead to activation of much more target enzymes)

Question 33

what does transduction involve

Answer 33

1) secondary messengers are turned on by og receptor that is activated by ligand - turn on other enzymes ex: cyclic AMP, calcium, cyclic GMP 2) Phosphorylation cascade -> protein kinases activate other enzymes by phosphorylating them ( adding p) - cAMP activates protein kinases (PKA) -> phosphorylate proteins (add phosphates) to activate or deactivate enzymes

Question 34

how is cAMP formed?

Answer 34

The enzyme Adenylyl Cyclase catalyzes the ATP and G-Proteins combine with it, changing the receptor. The Atp becomes cAMP and cAMP acts like a secondary messenger that activates other proteins. cAMP is degraded into AMP which destroys cAMP signal

Question 35

how cAMP activates protein kinase

Answer 35

cAMP binds to regulatory subunits which dissociate the complex, releasing active catalytic subunits which can phosphorylate target proteins.

Question 36

what is a protein kinase

Answer 36

an enzyme that catalyzes the transfer of phosphate group from ATP to proteins

Question 37

how are signals amplified?

Answer 37

many secondary messengers activated by og signals and many protein kinases are activated by that one secondary messenger, which amplifies the of signal

Question 38

what regulates protein synthesis?

Answer 38

-TF factors which affect transcription

Question 39

what could the response be?

Answer 39

- regulation of protein synthesis -regulate protein activity -modify gene expression -cellar metabolism -function -movement

Question 40

what does phosphate do?

Answer 40

its an allosteric activator for glycogen phosphorylate which chops up glycogen

Question 41

what are the three basic receptor pathways

Answer 41

1) g-protein coupled receptors (most common) 2) gated ion channel (channel opens) 3) enzyme-linked receptors (enzymes activated)

Question 42

how do g-protein-linked receptors work?

Answer 42

the first messenger is a signal molecule like epinephrine which goes to the g protein-coupled receptor which makes a g-protein which has GTP and it goes into the adenylyl cyclase which turns ATP into cyclic AMP which is a secondary messenger which activates protein kinase which then creates a response

Question 43

how do gated ion channels work?

Answer 43

So at first the ion gated is closed, keeping the ions on the outside but once the ligand connects to the channel, the gate opens which allows the ions to go into the cell, past the plasma membrane which then includes a cellular response, and once the ligand leaves the gate closes

Question 44

what could the channel gates be used for

Answer 44

muscle cell contractions

Question 45

what are some siganl pathways in unicellaur

Answer 45

-respond to environemnt - can communicate with nearby cells -pheromones can trigger reproduction - external signal triggers movement

Question 46

what are some multicellular signal pathways

Answer 46

-coordinate activities -coordinate atvities to support organsim -> epinephrine -> temp determination of sex in reptiles -> apoptosis -> cell specialization

Question 47

what are morphogens

Answer 47

they stimulate cell differentiation and development and they are a class of compounds in embryonic development

Question 48

what happens if signals are blocked

Answer 48

it can lead to deleterious like diseases, diabetes , cancer, posions, pesticides, and pathogens

Question 49

what are some preventative or prophylactic results if blocked?

Answer 49

anesthetics, antihistamines, birth control